The effect of prenatal and postnatal dietary exposures on childhood development of atopic disease

Mediterranean-Type Diets as a Protective Factor for Asthma and Atopy

We are currently riding the second wave of the allergy epidemic, which is ongoing in affluent societies, but now also affecting developing countries. This increase in the prevalence of atopy/asthma in the Western world has coincided with a rapid improvement in living conditions and radical changes in lifestyle, suggesting that this upward trend in allergic manifestations may be associated with cultural and environmental factors. Diet is a prominent environmental exposure that has undergone major changes, with a substantial increase in the consumption of processed foods, all across the globe. On this basis, the potential effects of dietary habits on atopy and asthma have been researched rigorously, but even with a considerable body of evidence, clear associations are far from established. Many factors converge to obscure the potential relationship, including methodological, pathophysiological and cultural differences. To date, the most commonly researched, and highly promising, candidate for exerting a protective effect is the so-called Mediterranean diet (MedDi). This dietary pattern has been the subject of investigation since the mid twentieth century, and the evidence regarding its beneficial health effects is overwhelming, although data on a correlation between MedDi and the incidence and severity of asthma and atopy are inconclusive. As the prevalence of asthma appears to be lower in some Mediterranean populations, it can be speculated that the MedDi dietary pattern could indeed have a place in a preventive strategy for asthma/atopy. This is a review of the current evidence of the associations between the constituents of the MedDi and asthma/atopy, with emphasis on the pathophysiological links between MedDi and disease outcomes and the research pitfalls and methodological caveats which may hinder identification of causality. MedDi, as a dietary pattern, rather than short-term supplementation or excessive focus on single nutrient effects, may be a rational option for preventive intervention against atopy and asthma.

Maternal serum 25-hydroxyvitamin D levels and infant atopic dermatitis: A prospective cohort study

BACKGROUND

Maternal vitamin D status during pregnancy has been linked with the risk of atopic dermatitis (AD) in children, while the results were inconsistent. The objective of this study was to assess the potential association.

METHODS

Serum 25-hydroxyvitamin D (25(OH)D) levels were measured in pregnant women from the birth cohort MKFOAD. Infant AD was diagnosed according to Williams' criteria. Multivariate logistic regression model was used to examine the association of maternal serum 25(OH)D levels in the first, second, and third trimester of gestation with the risk of infant AD at first year of age.

RESULTS

In total, 121 (26.5%) of 456 infants developed AD prior to 1 year of age. In general, higher maternal serum 25(OH)D levels throughout pregnancy were associated with increased risks of AD in infants prior to 1 year of age in multivariate logistic regression models, with borderline statistical significance in the first (per ln unit increase: adjusted OR = 1.93, 95% CI: 0.96, 3.88) and second (per ln unit increase: adjusted OR = 1.72, 95% CI: 0.93, 3.19) trimester. Multivariate logistic regression models using categorical variables of maternal 25(OH)D levels by tertiles showed similar results: Infants born to mothers with serum 25(OH)D levels in the highest tertile had higher risk of AD than those with 25(OH)D in the lowest tertile.

CONCLUSIONS

The present study found some evidence supporting that higher maternal 25(OH)D levels during pregnancy increased the risk of infant AD. However, the clinical implication of the findings should be limited for those with blood levels over the recommendations.

Role of antioxidants on the clinical outcome of patients with perennial allergic rhinitis

BACKGROUND

Antioxidants have a preventive or therapeutic role in oxygen free radical-mediated cell and tissue damage. The study aimed to investigate the therapeutic effects of antioxidants and intranasal steroid fluticasone furoate (FF) on the clinical outcome of patients with perennial allergic rhinitis.

METHODS

Subjects with perennial allergic rhinitis (n = 61) were randomly divided into two groups, group A (n = 30) received FF and group B (n = 31) received FF with antioxidants for 6 weeks. Nasal and ocular symptoms were evaluated weekly by using a four-point categoric scale. The efficacy of the study drug was assessed based on the mean change from baseline of the total daytime nasal symptom scores, total nighttime nasal symptom scores, and the composite symptom scores.

RESULTS

The combined therapy (FF with antioxidants) resulted in marked improvements (p ≤ 0.05) in the mean total daytime nasal symptom scores, total nighttime nasal symptom scores, and composite symptom scores of subjects compared with ones treated with intranasal steroid (FF) alone, which highlighted the therapeutic effect of antioxidants in allergic rhinitis.

CONCLUSION

Significant improvement in clinical outcome was observed in subjects who received antioxidants along with FF. However, because this was an open-label study, the results must be interpreted with caution, and further double-blind, placebo-controlled, dose-ranging trials supplemented with different antioxidants together with intranasal steroids are suggested.

Data resource profile: the Aarhus birth cohort biobank (ABC biobank)

Exposure during fetal life may have long-lasting health consequences for the child. Cohorts with biological material are necessary to investigate the possible biological mechanisms behind this potential early programming of disease. The Aarhus Birth Cohort Biobank was established in 2008 as an amendment to an ongoing research database, the Aarhus Birth Cohort. It aims to provide the opportunity to investigate the role of genetic factors, environmental exposures and lifestyles in pregnancy on the risk of disease in the offspring. All pregnant women who plan to give birth at Aarhus University Hospital, Skejby, and the fathers-to-be are invited to participate in the Aarhus Birth Cohort Biobank. Blood samples (mother 54 ml, father 4 ml) are drawn at the time of the routine ultrasound scanning in gestational week 12. At the same time, the women fill out a detailed questionnaire on medical and lifestyle factors. Immediately after birth, blood (10 ml) from the umbilical cord and umbilical cord tissue are sampled. Samples from the mothers are separated into plasma, buffy coat, erythrocyte suspension and serum before freezing at -80°C. Samples of whole blood are also stored, from both the mother and the father. Plasma, buffy coat, erythrocyte suspension and tissue from the umbilical cord are stored at -80°C. All researchers can apply for access to the database. For more details, see www.ab-biobank.dk or tbh@dadlnet.dk.

Fish and fish oil intake in relation to risk of asthma: a systematic review and meta-analysis

Although laboratory studies suggest that long-chain n-3 polyunsaturated fatty acids (LCn3PUFAs) may reduce risk of asthma, epidemiological data remain controversial and inconclusive. We quantitatively reviewed the epidemiological studies published through December 2012 in PubMed and EMBASE by using a fixed-effects or random-effects model. Eleven studies, comprised of 99,093 individuals (3,226 cases), were included in the final dataset. Of them, 7 studies examined associations between intake of fish or LCn3PUFA and risk of asthma: 4 studies in children (996 cases from 12,481 children) and 3 in adults (1,311 cases from 82,553 individuals). Two studies (69 cases from 276 infants) investigated LCn3PUFA levels in mothers' milk, and two studies assessed maternal fish consumption (786 cases from 2,832 individuals) during lactation and/or plasma LCn3PUFA levels during pregnancy (64 cases from 951 infants) in relation to offspring's asthma. The pooled relative risk of child asthma were 0.76 (95% CI, 0.61-0.94) for fish consumption and 0.71 (95% CI, 0.52-0.96) for LCn3PUFA intake. No statistically significant association was found in studies among adults. Epidemiological data to date indicate that fish or LCn3PUFA intake may be beneficial to prevent asthma in children. Further studies are needed to establish causal inference and to elucidate the potential mechanisms.

Diet and allergic diseases among population aged 0 to 18 years: myth or reality?

Allergic diseases are an important health problem. However, epidemiological studies concerning childhood diet-related allergic diseases are scarce. This review examines published articles dealing with diet, dietary patterns and nutrition in relation with allergic diseases among population aged 0 to 18 years. Studies and trials were identified using MEDLINE/PubMed and Cochrane Database of Systematic Reviews and were limited to those published in English or French from 1992 until 2012. This manuscript also reviews the evidence for maternal diet during pregnancy and diet during early childhood and their association with childhood atopic diseases, taking into account the methodology used to evaluate dietary patterns. The evidence reviewed is derived from large epidemiological studies exploring the effects of different food categories on asthma, atopic dermatitis, and allergic rhinitis in children. Overall, maternal diet during pregnancy and a childhood diet rich in antioxidants and omega-3 fatty acids are considered as healthy diets that could be protective for allergic diseases in childhood.

Improving asthma during pregnancy with dietary antioxidants: the current evidence

The complication of asthma during pregnancy is associated with a number of poor outcomes for the mother and fetus. This may be partially driven by increased oxidative stress induced by the combination of asthma and pregnancy. Asthma is a chronic inflammatory disease of the airways associated with systemic inflammation and oxidative stress, which contributes to worsening asthma symptoms. Pregnancy alone also intensifies oxidative stress through the systemic generation of excess reactive oxidative species (ROS). Antioxidants combat the damaging effects of ROS; yet antioxidant defenses are reduced in asthma. Diet and nutrition have been postulated as potential factors to combat the damaging effects of asthma. In particular, dietary antioxidants may play a role in alleviating the heightened oxidative stress in asthma. Although there are some observational and interventional studies that have shown protective effects of antioxidants in asthma, assessment of antioxidants in pregnancy are limited and there are no antioxidant intervention studies in asthmatic pregnancies on asthma outcomes. The aims of this paper are to (i) review the relationships between oxidative stress and dietary antioxidants in adults with asthma and asthma during pregnancy, and (ii) provide the rationale for which dietary management strategies, specifically increased dietary antioxidants, might positively impact maternal asthma outcomes. Improving asthma control through a holistic antioxidant dietary approach might be valuable in reducing asthma exacerbations and improving asthma management during pregnancy, subsequently impacting perinatal health.

Cord serum 25-hydroxyvitamin D and risk of early childhood transient wheezing and atopic dermatitis

BACKGROUND

There is increasing evidence of the effect of maternal vitamin D intake during pregnancy on the risk of asthma and allergic outcomes in offspring. However, studies on the relationship between cord levels of 25-hydroxyvitamin D (25[OH]D) and asthma and allergic diseases are very few.

OBJECTIVE

Our aim was to investigate the associations between cord serum 25(OH)D levels and asthma, wheezing, allergic rhinitis, and atopic dermatitis in the offspring from birth to 5 years.

METHODS

Cord blood samples were collected at birth and analyzed for 25(OH)D levels in 239 newborns from the Etude des Déterminants pré et post natals du développement et de la santé de l'Enfant (EDEN) birth cohort. The children were followed up until age 5 years by using International Study of Asthma and Allergies in Childhood-based symptom questionnaires.

RESULTS

The median cord serum level of 25(OH)D was 17.8 ng/mL (interquartile range, 15.1 ng/mL). By using multivariable-adjusted logistic regression models, a significant inverse association was observed between cord serum 25(OH)D levels and risk of transient early wheezing and early- and late-onset atopic dermatitis, as well as atopic dermatitis, by the ages of 1, 2, 3, and 5 years. We found no association between cord serum 25(OH)D levels and asthma and allergic rhinitis at age 5 years.

CONCLUSIONS

Cord serum 25(OH)D levels were inversely associated with the risk of transient early wheezing and atopic dermatitis by the age of 5 years, but no association was found with asthma and allergic rhinitis.

Nutrition and asthma

Over the past four decades, the prevalence of asthma has markedly increased in Westernized countries and countries transitioning to this lifestyle. It has been hypothesized that these increases are a consequence of changing environmental and/or behavioral factors. The modification of dietary habits (ie, decreased intake of fruits/vegetables and increased intake of "Westernized" processed foods) and a decrease in sun exposure have led to decreased intake of antioxidant vitamins and fatty acids and to decreased circulating levels of vitamin D, and have been proposed to explain the rise in asthma prevalence. This article summarizes the main findings on foods and nutrients connected to asthma based on several exhaustive recent reviews on the topic, and examines the evidence for an effect of dietary patterns on asthma. Overall, findings underscore the importance of conducting prospective studies and clinical trials to better understand the role of diet in the etiology of asthma.

Influence and mechanisms of maternal and infant diets on the development of childhood asthma

Perinatal nutrition has been implicated in the programming of diseases in children and adults. The prevalence of asthma has dramatically increased in the past few decades, particularly in children. This suggests that the perinatal environment, including maternal and infant diets, may be involved in the increase in the prevalence of asthma. Recent studies have demonstrated that certain maternal and infant diets have a protective or augmentative effect on the development of asthma. Maternal diets with higher vitamin D, vitamin E, or/and probiotics are related to asthma prevention. Infants with breast feeding for at least 4 months and/or complementary diets between 4 and 6 months may have regulatory effects on the prevention of asthma. In summary, diets may have epigenetic or immune regulatory effects on the promotion or prevention of asthma. This article analyzes recent reports on the potential mechanism and mechanism-driven early prevention of childhood asthma by modification of maternal and infant diets.

Fish consumption in infancy and asthma-like symptoms at preschool age

OBJECTIVE

To assess whether timing of introduction of fish and the amount of fish consumption in infancy were associated with asthmalike symptoms at preschool age.

METHODS

This study was embedded in the Generation R study (a population-based birth cohort in Rotterdam, Netherlands). At the age of 12 and 14 months, timing of introduction of fish into the infant's diet was assessed. The amount of fish consumption at 14 months was assessed by a semiquantitative food frequency questionnaire. Presence of asthmalike symptoms in the past year was assessed at the child's age of 36 and 48 months.

RESULTS

Relative to no introduction in the first year of life, introduction between age 6 and 12 months was significantly associated with a lower risk of wheezing at 48 months (odds ratio [OR]: 0.64; 95% CI: 0.43-0.94). When compared with introduction between 6 and 12 months, no introduction in the first year and introduction between 0 and 6 months were associated with an increased risk of wheezing at 48 months (OR: 1.57; 95% CI: 1.07-2.31 and OR: 1.53; 95% CI: 1.07-2.19, respectively). The amount of fish at age 14 months was not associated with asthmalike symptoms (P > .15).

CONCLUSIONS

Introduction of fish between 6 and 12 months but not fish consumption afterward is associated with a lower prevalence of wheezing. A window of exposure between the age of 6 and 12 months might exist in which fish might be associated with a reduced risk of asthma.

Ambient air pollution and allergic diseases in children

The prevalence of allergic diseases has increased worldwide, a phenomenon that can be largely attributed to environmental effects. Among environmental factors, air pollution due to traffic is thought to be a major threat to childhood health. Residing near busy roadways is associated with increased asthma hospitalization, decreased lung function, and increased prevalence and severity of wheezing and allergic rhinitis. Recently, prospective cohort studies using more accurate measurements of individual exposure to air pollution have been conducted and have provided definitive evidence of the impact of air pollution on allergic diseases. Particulate matter and ground-level ozone are the most frequent air pollutants that cause harmful effects, and the mechanisms underlying these effects may be related to oxidative stress. The reactive oxidative species produced in response to air pollutants can overwhelm the redox system and damage the cell wall, lipids, proteins, and DNA, leading to airway inflammation and hyper-reactivity. Pollutants may also cause harmful effects via epigenetic mechanisms, which control the expression of genes without changing the DNA sequence itself. These mechanisms are likely to be a target for the prevention of allergies. Further studies are necessary to identify children at risk and understand how these mechanisms regulate gene-environment interactions. This review provides an update of the current understanding on the impact of air pollution on allergic diseases in children and facilitates the integration of issues regarding air pollution and allergies into pediatric practices, with the goal of improving pediatric health.

Innate immunity in allergic disease

The innate immune system consists of multiple cell types that express germline-encoded pattern recognition receptors that recognize pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs). Allergens are frequently found in forms and mixtures that contain PAMPs and DAMPs. The innate immune system is interposed between the external environment and the internal acquired immune system. It is also an integral part of the airways, gut, and skin. These tissues face continuous exposure to allergens, PAMPs, and DAMPs. Interaction of allergens with the innate immune system normally results in immune tolerance but, in the case of allergic disease, this interaction induces recurring and/or chronic inflammation as well as the loss of immunologic tolerance. Upon activation by allergens, the innate immune response commits the acquired immune response to a variety of outcomes mediated by distinct T-cell subsets, such as T-helper 2, regulatory T, or T-helper 17 cells. New studies highlighted in this review underscore the close relationship between allergens, the innate immune system, and the acquired immune system that promotes homeostasis versus allergic disease.

Association of ozone exposure with asthma, allergic rhinitis, and allergic sensitization

BACKGROUND

Children are vulnerable to air pollution, which is known to be related to the recent increasing trend of allergic disease.

OBJECTIVE

To investigate the effects of air pollution on respiratory allergic diseases in school children.

METHODS

A prospective survey of parental responses to International Study of Asthma and Allergies in Childhood questionnaires, together with allergy evaluation, was conducted in 1743 school children selected from metropolitan cities and industrial areas during a 2-year period. Individual exposure to air pollution was estimated by using a geometric information system with the 5-year mean concentration of air pollutants.

RESULTS

A total of 1,340 children (male:female ratio, 51.4:48.6) with a mean (SD) age of 6.84 (0.51) years were included in the analysis. Each child underwent allergy evaluation at the time of enrollment and at a 2-year follow-up. After 2 years, the 12-month prevalence of wheezing was significantly decreased, whereas the lifetime prevalence of allergic rhinitis showed a significant increase. Ozone exposure was significantly associated with the 12-month prevalence of wheeze (odds ratio per 5 ppb, 1.372; 95% confidence interval, 1.016-1.852). Ozone was also associated with allergic rhinitis in children who reside in industrial areas. In addition, significant positive associations between ozone and the rate of newly developed sensitization to outdoor allergen were found (P for trend = .007).

CONCLUSION

Exposure to ozone was associated with current wheeze and allergic rhinitis. An increased rate of newly developed sensitization to outdoor allergen by ozone may explain the association.

Maternal dietary pattern during pregnancy is not associated with recurrent wheeze in children

BACKGROUND

The rise in asthma prevalence over the last few decades may be a result of changes in prenatal or early-life environment, including maternal diet during pregnancy. Previous studies have found associations between individual foods or nutrients consumed during pregnancy and asthma or wheeze in children, but these may be confounded by overall dietary pattern.

OBJECTIVE

To determine whether overall maternal dietary pattern during pregnancy is associated with recurrent wheeze in children.

METHODS

A total of 1376 mother-infant pairs from Project Viva, a longitudinal prebirth cohort, who had responses for food frequency questionnaires in the first and second trimester and outcome data at 3 years of age were included. Multivariable logistic regression was used to look at associations between dietary pattern and the primary outcome of recurrent wheeze at 3 years. Overall dietary pattern was examined by using Mediterranean diet score, Alternate Healthy Eating Index modified for pregnancy (AHEI-P), and principal components analysis to look at Western and Prudent diets.

RESULTS

None of these dietary patterns was associated with the primary outcome of recurrent wheeze in children in either the crude or the multivariable model (multivariable model, odds ratio per 1-point increase in Mediterranean diet, 0.98 [95% CI, 0.89-1.08]; AHEI-P, 1.07 [0.87-1.30]; Prudent, 1.02 [0.83-1.26]; Western, 0.98 [0.81-1.19]).

CONCLUSION

Overall dietary pattern during pregnancy is not associated with recurrent wheeze in this cohort. Maternal intake of individual nutrients may be more important determinants of offspring wheeze-associated illness than is dietary pattern.